This invention relates generally to molded case electrical circuit breakers of the type wherein the case is formed by two half-cases abutted together to jointly form the case and the meeting of a European safety standard for such circuit breakers by economically modifying a known case.
With the increasing emphasis on exports so as to minimize the balance of payments trade deficit of our country, engineers involved in the design of electrical equipment for export such as circuit breakers, must design the equipment to comply not only with the requirements of the United States National Electrical Code (NEC) and of Underwriters Laboratories, Inc. (UL), but also of other countries.
Guidance for design engineers can be found in the safety standards of the International Electro Technical Commission (IEC) and the safety standards set forth in the West German Verband Deutscher Elektrotechniker e.V. (VDE) codes.
For circuit breakers, the IEC and VDE codes require 8 mm clearance and creepage distances between any operator accessible part of the circuit breaker and a hazardous voltage within the circuit breaker.
This invention is directed to providing such minimum 8 mm clearance and creepage distances in molded case circuit breakers of existing design and construction with a minimum of change in the design and construction thereof.
Additional information on the IEC and VDE codes may, of course, be obtained from the codes themselves and from an article entitled "Meeting Circuit Breaker Safety Standards at Home and Abroad" appearing in Design News issue of Sept. 21, 1981 at pages 86 to 92, inclusive.